X-ray imaging is applied in various technical fields in order to obtain information about internal structures within a region of interest of an object. For example, medical X-ray imaging devices are used to obtain information about internal structures within a patient's body. Phase contrast imaging, e.g. using an interferometer, has been developed to provide higher contrast, especially in soft tissue and other low-absorbing materials. At the same time, the interferometer may also yield a dark-field signal, related to small-angle scattering from structures smaller than the spatial resolution of the detector. The phase information may be acquired using a phase stepping method, which may require multiple exposures.
Phase contrast imaging requires phase-stepping, i.e. a phase grating is scanned along in order to retrieve phase information. That is, several projections are acquired for different positions of the grating. Phase contrast imaging procedures therefore require significantly more time when compared to conventional X-ray applications. Furthermore, the required use of an absorption grid or structured scintillator implies that a considerable amount of X-ray photons passing a patient are discarded, resulting in a poor X-ray dose efficiency. For example, US 2014/0177795 A1 describes an electronic phase stepping method for acquiring the phase information. Also WANG DAJIANG ET AL: “A dual detector approach for X-ray differential phase contrast imaging”, RADIATION PHYSICS AND CHEMISTRY, vol. 95, 31 Dec. 2012 (2012-12-31), pages 86-90, XP028793259, ISSN: 0969-806X, 001: 10.1016/J.RADPHYSCHEM.2012.12.027 and RUTISHAUSER SIMON ET AL: “Structured scintillator for hard x-ray grating interferometry”, APPLIED PHYSICS LETTERS, A 1 P PUBLISHING LLC, US, vol. 98, no. 17, 27 Apr. 2011 (2011-04-27), pages 171107-1-171107-3, XP012140442, ISSN: 0003-6951, 001: 10.1063/1.3583464 refer to this field.